The invention relates to an improved clipless pedal for attaching an appropriate cleat on a bicycle rider""s shoe to the pedal. More particularly, it reduces the weight, complexity and cost of manufacture while improving performance of existing pedal systems by making the spring that retains the shoe-mounted cleat itself the complete cleat retention mechanism on the pedal.
Clipless pedals are a popular and effective method of attaching a bicycle rider""s feet to a bicycle crankarm. Such pedals generally consist of a component attached to the rider""s shoe and another on the pedal, one of which is spring-loaded. With most clipless pedals, riders enter the mechanism by stepping down and exit by twisting the foot.
A large number of clipless pedal designs have been marketed over the last ten years. A large percentage of these have been based on the xe2x80x9cSPDxe2x80x9d design first marketed by Shimano starting around 1990. This system consists in its most basic aspects of (i) a small metal cleat attached to the cyclist""s shoe, (ii) two clamps mounted to the body of the pedal and shaped to clasp the front and rear edges of the cleat, at least one of which is mounted on so that it pivots about an axis defined by a screw or rod and is biased by a coiled spring, and (iii) a steel plate mounted to the pedal body upon which the cleat rests once it is engaged in the pedal by the clamps. In the case of symmetrically two-sided pedals, which are commonly used in off-road riding on mountain bikes, there are two sets of these components, one set on each of the top and bottom surfaces of the pedal.
A large number of variations on this basic architecture have been produced. The vast majority of these have used helically coiled steel springs mounted on shafts as the spring mechanism. These springs, along with the hardware and reinforcements required to locate, support and translate forces from one plane to another, add considerable weight, complication and expense to these designs. Most such designs include 4 such springs. In the case of off-road pedals, where mud-clearing is a major consideration, these additional components also add bulk and reduce the ability of the system to shed mud, thus making it more difficult to use the system in challenging conditions, especially if the rider is focused on racing or challenging off-road conditions.
The first SPD system marketed by Shimano allowed both the front and rear clamping means to pivot. This allowed the rider to step straight down into the pedal, as the camming surfaces on the cleat would interact with the clamping mechanisms to open the mechanisms sufficiently to allow the cleat to pass straight downward into the xe2x80x9cinxe2x80x9d position. The two clamps would then spring back into the closed position, holding the cleat in place until the rider exited by twisting his foot. Because these pedals, like nearly all off-road pedals, are symmetrically two-sided, each pedal thus had four pivoting clamps mounted on two separate shafts. The additional moving parts and related support structure required to allow this movement added considerable weight, cost and complexity.
In order to reduce weight and complexity, most current designs pivot only the rear clamping means. The front clamping means is generally fixed relative to the pedal body. This means that the rider generally cannot step straight down into the pedal, but must begin the engagement motion by starting with the foot behind the correct position, push the front edge of the cleat into the front clamping means by sliding the foot forward, and then step downward. This two step process makes entry more difficult and less reliable.
One prior design, the Onza pedal system, used two flat steel plates in place of the pivoting clamps. These plates had small windows into which the engaging means of the cleat were inserted, and the plates were urged toward the engaging position by elastomers. Like the first SPD pedal system, the Onza allowed both the front and rear engaging means to move relative to the cleat. Though simpler and lighter than the standard SPD design, the Onza design required a bulky pedal body to mount the separate steel plates and elastomers, and was less effective than the standard pedal because elastomers proved to be less desirable as a spring means.
More recently, the Kore pedal has combined certain features of the Onza pedal, such as the flat rear plate engagement means and elastomer spring, with a more traditional fixed engaging means on the front of the mechanism. As with the instant invention, the clamping means are integral with the cleat plate. However, because the front engaging means is fixed, the Kore pedal does not allow true step-down entry. The configuration of the clamping means does not permit both ends of the engaging means to move relative to the cleat. The Kore pedal also uses elastomers as part of their retention means.
It is an object of the present invention to provide a simpler pedal design that is easier to manufacture and assemble. It is another object of the present invention to provide a pedal design that is lighter in weight. It is a further object of the invention to provide a design with superior performance in dirty environments. It is a further object of the present invention to provide a design that allows step-down entry without a weight penalty. These and other advantages of the present invention will be evident to one of ordinary skill in the art in the following description.
The invention involves a unique pedal, which employs a particular type of spring plate or clamp, and which preferably interacts with a relatively conventional cleat to attach the shoe and foot of a rider to the drank arm of a relatively conventional bicycle. Thus, aspects of the invention concern the spring plate, the pedal, the pedal and clip, and the bicycle with such a pedal, as will be apparent from the following summary of the invention.
The pedal of the invention includes a body with opposed sides, one being referred to as the top and the other the bottom. A generally C-shaped spring plate has a mid portion for attachment to one side of the pedal body, and arms extending from generally opposite ends of the mid portion about the pedal body to terminate in end portions that lie generally in a plane somewhat beyond the other side of the body. The end portions are shaped to removably receive and hold a cleat attached to a bike rider""s shoe.
Preferably the pedal body includes two such spring plates, the plates being attached to opposed sides of the body and their arms being shaped and located to clear one another and lie in a plane spaced from the spring plate on the other side. Thus, by such an arrangement the rider can engage a cleat on his shoe with a spring plate on the pedal body, thereby to power a bicycle. Also, preferably the arms of the spring plate include two arms on one side and one arm on the other side, the two arms being spaced sufficiently to allow the single arm of the opposed spring plate to pass between them. The arms are sufficiently resilient to allow the cleat to cam them apart as the rider steps his cleat into engagement with the pedal, but sufficiently rigid to resist removal of the clear during normal pedaling of the bicycle.
Preferably the end portions of the spring plate are shaped to cooperate with appropriately shaped portions of the cleat to allow the rider to cam the cleat into engagement with the pedal by stepping onto the pedal, and to allow the rider to disengage the cleat form the pedal by twisting the cleat out of the pedal. In another embodiment a window is provided in the end portion for this purpose. A tension plate may be added to adjust the resiliency of the spring plate if desired.